Running is a high-impact cardio exercise that often causes blood sugar to drop during or after the activity. For people with diabetes, blood sugar after running may fall quickly, stay low for hours, or drop later the same day depending on pace, distance, and insulin timing. This applies to both type 1 and type 2 diabetes.
Because running uses glucose rapidly, understanding its effects helps prevent exercise-related lows.
What happens to blood sugar during running
Running requires continuous energy, and muscles pull glucose directly from the bloodstream. At the same time, insulin sensitivity increases, allowing cells to absorb glucose more efficiently.
As a result:
- Blood sugar often drops during running
- Longer runs increase hypoglycemia risk
- Faster or intense runs may cause brief spikes, followed by drops
This is why runners with diabetes need closer monitoring than with strength workouts.
Blood sugar before, during, and after running
Before running
Starting a run with low blood sugar increases the risk of hypoglycemia. Running should follow basic exercise safety for people with diabetes guidelines, especially for those using insulin.
During running
Blood sugar typically falls steadily, particularly during moderate or long-distance runs. Symptoms of low blood sugar can appear quickly if carbs are not available.
After running
Blood sugar may remain lower for several hours, and delayed lows are common later in the day or overnight. This effect is stronger after long or intense sessions.
Is running safe for people with diabetes?
Running is generally safe for people with diabetes when planned properly. The American Diabetes Association recommends aerobic exercise like running for improving glucose control and cardiovascular health.
However, running lowers blood sugar more aggressively than strength training with diabetes, making preparation and monitoring essential.
Tips to prevent low blood sugar when running
- Check blood sugar before and after runs
- Carry fast-acting carbohydrates
- Avoid running during peak insulin action
- Consider a small carb snack before longer runs
- Monitor blood sugar later the same day
People with type 1 diabetes may require insulin adjustments under medical guidance.
When to avoid running
Avoid running if blood sugar is very low, extremely high with symptoms, or if ketones are present. Illness, dehydration, or dizziness are also reasons to postpone exercise.
FAQ
Does running always lower blood sugar?
Most of the time, yes. Very intense or sprint-style running may briefly raise blood sugar before it drops.
Is running riskier than walking for diabetes?
Yes. Running uses glucose faster and increases the chance of lows compared to lower-intensity cardio. For a broader comparison, see blood sugar after cardio exercise.
Final thoughts
Blood sugar after running often drops during or after the workout, sometimes hours later. With proper planning, monitoring, and recovery, running can be a safe and effective part of diabetes management.
This article is for general information only and does not replace medical advice. People with diabetes should consult their healthcare provider before changing exercise routines.
